rust: dma: Update ARef and AlwaysRefCounted imports from sync::aref

Update call sites in the dma subsystem to import `ARef` and
`AlwaysRefCounted` from `sync::aref` instead of `types`.

This aligns with the ongoing effort to move `ARef` and
`AlwaysRefCounted` to sync.

Suggested-by: Benno Lossin <lossin@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1173
Signed-off-by: Shankari Anand <shankari.ak0208@gmail.com>
Link: https://lore.kernel.org/r/20250814104133.350093-1-shankari.ak0208@gmail.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/kernel/dma.rs

@@ -9,8 +9,8 @@
     device::{Bound, Core},
     error::{to_result, Result},
     prelude::*,
+    sync::aref::ARef,
     transmute::{AsBytes, FromBytes},
-    types::ARef,
 };
 
 /// Trait to be implemented by DMA capable bus devices.

samples/rust/rust_dma.rs

@@ -10,7 +10,7 @@
     dma::{CoherentAllocation, Device, DmaMask},
     pci,
     prelude::*,
-    types::ARef,
+    sync::aref::ARef,
 };
 
 struct DmaSampleDriver {